Mid-infrared emissivity of partially dehydrated asteroid (162173) Ryugu shows strong signs of aqueous alteration.

The near-Earth asteroid (162173) Ryugu, the target of Hayabusa2 space mission, was observed via both orbiter and the lander instruments. The infrared radiometer on the MASCOT lander (MARA) is the only instrument providing spectrally resolved mid-infrared (MIR) data, which is crucial for establishing a link between the asteroid material and meteorites found on Earth. Earlier studies revealed that the single boulder investigated by the lander belongs to the most common type found on Ryugu. Here we show the spectral variation of Ryugu's emissivity using the complete set of in-situ MIR data and compare it to those of various carbonaceous chondritic meteorites, revealing similarities to the most aqueously altered ones, as well as to asteroid (101955) Bennu. The results show that Ryugu experienced strong aqueous alteration prior to any dehydration.

The best temperature range to acquire reliable thermal infrared spectra from orbit.

Solar System bodies undergo to daily and periodical variations of temperature that mainly depend on their closeness to the Sun. It is known that mineral expansion and contraction due to such variations modify the thermal infrared spectra acquired on solid surfaces. Therefore, it becomes crucial to know the best temperature range at which the acquisition itself should be carried out to get reliable information on the mineralogy of such bodies. Here we provide the thermal expansion of olivine between 20 and 298 K determined by X-ray diffraction. Our data reveal the non-linear behaviour of silicates that undergo to low temperatures, where volume variations appear positively correlated with temperatures. Subtle bond-length variations occurring at low temperatures are then expected to minimally affect vibrational absorption positions. We suggest that thermal infrared spectra of those Solar-System surfaces that are not exceeding 300 K provide reliable information about not only the silicate mineral identification but also on their chemical composition, regardless of the instantaneous temperature.

Deriving iron contents from past and future Venus surface spectra with new high-temperature laboratory emissivity data.

In situ information on the surface composition of Venus is based on measurements of a small number of landing sites. In the laboratory, we measured the emissivity of a range of igneous rocks at temperatures up to 480°C. We show that high-temperature laboratory spectra of basalts are consistent with the only existing multispectral data from the surface of Venus obtained by the photometers on the Venera 9 and 10 landers. We derive the FeO abundances for these landing sites of 12.2 and 9.5 weight %, respectively. From orbit, Venus' surface is only observable on the nightside through small spectral windows near 1 µm where the CO2 atmosphere is largely transparent. The new laboratory data show that different rock types can be distinguished using only a small set of spectral bands. Therefore, future orbital spectral observations can provide a much-needed global composition map.

A dynamic upper atmosphere of Venus as revealed by VIRTIS on Venus Express.

The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90-120 km altitude) of Venus can be used to investigate the energetics and to trace the circulation of this hitherto little-studied region. Previous spacecraft and ground-based observations of infrared emission from CO2, O2 and NO have established that photochemical and dynamic activity controls the structure of the upper atmosphere of Venus. These data, however, have left unresolved the precise altitude of the emission owing to a lack of data and of an adequate observing geometry. Here we report measurements of day-side CO2 non-local thermodynamic equilibrium emission at 4.3 microm, extending from 90 to 120 km altitude, and of night-side O2 emission extending from 95 to 100 km. The CO2 emission peak occurs at approximately 115 km and varies with solar zenith angle over a range of approximately 10 km. This confirms previous modelling, and permits the beginning of a systematic study of the variability of the emission. The O2 peak emission happens at 96 km +/- 1 km, which is consistent with three-body recombination of oxygen atoms transported from the day side by a global thermospheric sub-solar to anti-solar circulation, as previously predicted.

South-polar features on Venus similar to those near the north pole.

Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright 'dipole' feature surrounded by a cold 'collar' at its north pole. The polar dipole is a 'double-eye' feature at the centre of a vast vortex that rotates around the pole, and is possibly associated with rapid downwelling. The polar cold collar is a wide, shallow river of cold air that circulates around the polar vortex. One outstanding question has been whether the global circulation was symmetric, such that a dipole feature existed at the south pole. Here we report observations of Venus' south-polar region, where we have seen clouds with morphology much like those around the north pole, but rotating somewhat faster than the northern dipole. The vortex may extend down to the lower cloud layers that lie at about 50 km height and perhaps deeper. The spectroscopic properties of the clouds around the south pole are compatible with a sulphuric acid composition.

Conditions of pressure scanning of a Fabry-Perot interferometer over a wide spectrum range.

The association of a Michelson interferometer and a Fabry-Perot etalon enables the control of the displacement of the peaks of Fabry-Perot transmittance by pressure scanning through Michelson fringes counting. Assuming the variations of the refractive index of gas as a function of wavenumber, pressure, and temperature are known, we show that it is perfectly possible to compute the number of fringes to shift in order to position a chosen peak of Fabry-Perot transmittance for any point in the spectrum. These possibilities enable us to build a real spectrometer whose accuracy is better than 0.05 cm(-1) in the whole visible range.

Electrochemical sterilization of beer.

Electrochemical inactivation of microorganisms was not achieved in beer but was achieved in physiological saline. Addition of carbohydrates or proteins to physiological saline prevented inactivation in this medium.

Evaluation of a stroma-free hemoglobin solution for use as a plasma expander.

The preparation of large quantities of a stable, stroma-free hemoglobin solution without coagulant activity is described. Following infusion of this solution into phlebotomized dogs, there is no methemoglobin formation, no adverse effects on vital signs, and no demonstrable activation of blood coagulation. The hemoglobin maintains its oxygen-carrying capacity and liberates oxygen into tissues. Acute and chronic effects on renal function following infusion of this preparation were also studied and no effect on clearance of urea, creatinine, or P.A.H. could be demonstrated. There was no change in urinary output and histological sections revealed no lesions attributable to hemoglobin toxicity. It is concluded that a stroma-free hemoglobin solution may have use as a plasma expander.